SWI-Prolog HTTP support library

This directory provides the SWI-Prolog libraries for accessing and providing HTTP services.

Client library

The main client library is library(http/http_open), which can open both HTTP and HTTPS connections and handle all request methods.

Server library

The main server libraris are

• library(http/thread_httpd) implements the server
• library(http/http_dispatch) implements binding locations predicates
• library(http/http_unix_daemon) implements integration in various Unix server managers and in general provides a suitable entry point for HTTP servers on Unix.
• library(http/html_write) implements generating HTML
• library(http/http_json) implements reading and writing JSON documents.

For simplicity, you can use library(http/http_server), which combines the typical HTTP libraries that most servers need. The idea of a common request handling system and three controlling libraries is outdated; the threaded server now being the only sensible controlling library.

Requirements

This library uses functionality from the ssl package to support HTTPS, the sgml package to read XML/HTML and the clib package for various extensions.

Prolog files

ax.pl  -- Attribute Exchange library
ax_alias/2	True when Alias is an alias name for the AX schema URL.
ax_form_attributes/2	True if Values is a list Alias(Value) for each exchanged attribute.
http_ax_attributes/2	True when HTTPAttributes is a list of Name=Value pairs that can be used with an HTTP request to query for the attributes Spec.
graphql.pl  -- GraphQL interface
graphql/4	Quasi-quotation syntax for embedding GraphQL in Prolog text.
graphql_auth_token_hook/2	Multifile, dynamic hook.
graphql_document_to_codes/3	Serialize Document, a Prolog term representing a GraphQL document as obtained from graphql_read_document/3 or the graphql/4 quasi-quotation, and unify Codes with the resulting list of character codes.
graphql_document_to_string/3	Serialize the GraphQL document Document and unify String with the resulting string.
graphql_execute_document/4	Send GraphQL document Document to be executed by the GraphQL endpoint at URI.
graphql_read_document/3	True when Document is a term representing the abstract syntax tree obtained from parsing Source as a GraphQL executable document.
html_head.pl  -- Automatic inclusion of CSS and scripts links
html_current_resource/1	True when About is a currently known resource.
html_insert_resource/3	Actually include HTML head resources.
html_requires/3	Include ResourceOrList and all dependencies derived from it and add them to the HTML head using html_post/2.
html_resource/2	Register an HTML head resource.
mime_include/4	Hook called to include a link to an HTML resource of type Mime into the HTML head.
html_quasiquotations.pl  -- HTML quasi quotations
html/4	The predicate html/4 implements HTML quasi quotations.
html_write.pl  -- Write HTML text
html/3	Generate HTML from Content.
html_begin/3	For html_begin//1, Env is a term Env(Attributes); for html_end//1 it is the plain environment name.
html_current_option/1	True if Option is an active option for the HTML generator.
html_end/3	For html_begin//1, Env is a term Env(Attributes); for html_end//1 it is the plain environment name.
html_header_hook/1	This multifile hook is called just before the Content-type header is emitted.
html_meta/1	This directive can be used to declare that an HTML rendering rule takes HTML content as argument.
html_post/4	Reposition HTML to the receiving Id.
html_print_length/2	Determine the content length of a token list produced using html//1.
html_quoted/3	Quote the value for normal (CDATA) text.
html_quoted_attribute/3	Quote the value according to the rules for tag-attributes included in double-quotes.
html_receive/3	Receive posted HTML tokens.
html_receive/4	This extended version of html_receive//1 causes Handler to be called to process all messages posted to the channal at the time output is generated.
html_root_attribute/4	Add an attribute to the HTML root element of the page.
html_set_options/1	Set options for the HTML output.
layout/3	Define required newlines before and after tags.
page/3	Generate a page including the HTML <!DOCTYPE> header.
page/4	Generate a page including the HTML <!DOCTYPE> header.
print_html/1	Print list of atoms and layout instructions.
print_html/2	Print list of atoms and layout instructions.
reply_html_page/2	Provide the complete reply as required by http_wrapper.pl for a page constructed from Head and Body.
reply_html_page/3	Provide the complete reply as required by http_wrapper.pl for a page constructed from Head and Body.
reply_html_partial/1	Reply with partial HTML document.
xhtml_ns/4	Demand an xmlns:id=Value in the outer html tag.
http_authenticate.pl  -- Authenticate HTTP connections using 401 headers
http_client.pl  -- HTTP client library
post_data_hook/3	Hook to extend the datatypes supported by the post(Data) option of http_open/3.
http_convert_data/4	Multi-file hook to convert a HTTP payload according to the Content-Type header.
http_delete/3	Execute a DELETE method on the server.
http_disconnect/1	Close down some connections.
http_get/3	Get data from a URL server and convert it to a suitable Prolog representation based on the Content-Type header and plugins.
http_patch/4	Issue an HTTP PATCH request.
http_post/4	Issue an HTTP POST request.
http_put/4	Issue an HTTP PUT request.
http_read_data/3	Read data from an HTTP connection and convert it according to the supplied to(Format) option or based on the Content-type in the Request.
http_cookie.pl  -- HTTP client cookie handling
update_cookies/3	Update the client cookie database.
write_cookies/3	Emit a cookie header for the current request.
cookie_remove_all_clients/0	Simply logout all clients.
cookie_remove_client/1	Fake user quitting a browser.
http_cors.pl  -- Enable CORS: Cross-Origin Resource Sharing
cors_enable/0	Emit the HTTP header Access-Control-Allow-Origin using domains from the setting http:cors.
cors_enable/2	CORS reply to a Preflight OPTIONS request.
http_digest.pl  -- HTTP Digest authentication
authenticate/3	Plugin for library(http_dispatch) to perform basic HTTP authentication.
authenticate_client/2	This hooks is called by http_open/3 with the following Action value:.
http_digest_challenge/4	Generate the content for a 401 WWW-Authenticate: Digest header field.
http_digest_password_hash/4	Compute the password hash for the HTTP password file.
http_digest_response/5	Formulate a reply to a digest authentication request.
http_parse_digest_challenge/2	Parse the value of an HTTP WWW-Authenticate header into a list of Name(Value) terms.
http_dirindex.pl  -- HTTP directory listings
mime_type_icon/2	Multi-file hook predicate that can be used to associate icons to files listed by http_reply_dirindex/3.
directory_index/4	Show index for a directory.
http_reply_dirindex/3	Provide a directory listing for Request, assuming it is an index for the physical directrory Dir.
http_dispatch.pl  -- Dispatch requests in the HTTP server
http_404/2	Reply using an "HTTP 404 not found" page.
http_current_handler/2	True if Location is handled by Closure.
http_current_handler/3	Resolve the current handler and options to execute it.
http_delete_handler/1	Delete handler for Spec.
http_dispatch/1	Dispatch a Request using http_handler/3 registrations.
http_handler/3	Register Closure as a handler for HTTP requests.
http_link_to_id/3	HREF is a link on the local server to a handler with given ID, passing the given Parameters.
http_location_by_id/2	True when Location represents the HTTP path to which the handler with identifier ID is bound.
http_redirect/3	Redirect to a new location.
http_reload_with_parameters/3	Create a request on the current handler with replaced search parameters.
http_reply_file/3	Options is a list of.
http_request_expansion/2	Register Goal for expanding the HTTP request handler.
http_safe_file/2	True if FileSpec is considered safe.
http_switch_protocol/2	Send an "HTTP 101 Switching Protocols" reply.
http_dyn_workers.pl  -- Dynamically schedule HTTP workers.
http_error.pl  -- Decorate uncaught HTTP exceptions with stack-trace
http_exception.pl  -- Map Prolog exceptions to HTTP errors
bad_request_error/2	If an exception of the term error(Formal, context(Stack, Context)) is caught and subsumes_term(ContextTemplate, Context) is true, translate the exception into an HTTP 400 exception.
in_or_exclude_backtrace/2	Remove the stacktrace from the exception, unless setting http:client_backtrace is true.
map_exception_to_http_status/4	Map certain exceptions to HTTP status codes.
http_files.pl  -- Serve plain files from a hierarchy
http_reply_from_files/3	HTTP handler that serves files from the directory Dir.
http_header.pl  -- Handling HTTP headers
http_hook.pl  -- HTTP library hooks
convert_parameter/3	Hook to execute a step in the HTTP parameter conversion process.
http_connection_over_proxy/6	Try to connect to the host Endpoint via Proxy for the purposes of retrieving the resource identified by URLParts.
http_host.pl  -- Obtain public server location
http_current_host/4
http_public_host/4	Current global host and port of the HTTP server.
http_public_host_url/2	True when URL is the public URL at which this server can be contacted.
http_public_url/2	True when URL is an absolute URL for the current request.
http_json.pl  -- HTTP JSON Plugin module
post_data_hook/3	Hook implementation that allows http_post_data/3 posting JSON objects using one of the forms below.
http_convert_data/4	Hook implementation that supports reading JSON documents.
http_read_json/2	Extract JSON data posted to this HTTP request.
http_read_json/3	Extract JSON data posted to this HTTP request.
http_read_json_dict/2	Similar to http_read_json/2,3, but by default uses the version 7 extended datatypes.
http_read_json_dict/3	Similar to http_read_json/2,3, but by default uses the version 7 extended datatypes.
is_json_content_type/1	True if ContentType is a header value (either parsed or as atom/string) that denotes a JSON value.
json_type/1	True if MediaType is a JSON media type.
reply_json/1	Formulate a JSON HTTP reply.
reply_json/2	Formulate a JSON HTTP reply.
reply_json_dict/1	As reply_json/1 and reply_json/2, but assumes the new dict based data representation.
reply_json_dict/2	As reply_json/1 and reply_json/2, but assumes the new dict based data representation.
http_load.pl  -- Load Prolog code from a web server
prolog_load_file/2	Hook into load_files/2 that loads http:// and https:// resources directly from the web.
http_log.pl  -- HTTP Logging module
http_multipart_plugin.pl  -- Multipart form-data plugin
http_convert_data/4	Convert multipart/form-data messages for http_read_data/3.
http_open.pl  -- HTTP client library
http_openid.pl  -- OpenID consumer and server library
openid_associate/3	Calls openid_associate/4 as.
openid_associate/4	Associate with an open-id server.
openid_authenticate/4	Succeeds if Request comes from the OpenID server and confirms that User is a verified OpenID user.
openid_current_host/3	Find current location of the server.
openid_current_url/2	Find the public URL for Request that we can make available to our identity provider.
openid_grant/1	Handle the reply from checkid_setup_server/3.
openid_hook/1	Call hook on the OpenID management library.
openid_logged_in/1	True if session is associated with OpenID.
openid_login/1	Associate the current HTTP session with OpenID.
openid_login_form/4	Create the OpenID form.
openid_logout/1	Remove the association of the current session with any OpenID.
openid_server/2	Realise the OpenID server.
openid_server/3	True if OpenIDLogin is the typed id for OpenID verified by Server.
openid_user/3	True if OpenID is a validated OpenID associated with the current session.
openid_verify/2	Handle the initial login form presented to the user by the relying party (consumer).
ssl_verify/5	Accept all certificates.
http_parameters.pl  -- Extract parameters (GET and POST) from HTTP requests
http_convert_parameter/4	Conversion of an HTTP form value.
http_convert_parameters/2	Implements the parameter translation of http_parameters/2 or http_parameters/3.
http_convert_parameters/3	Implements the parameter translation of http_parameters/2 or http_parameters/3.
http_parameters/2	Get HTTP GET or POST form-data, applying type validation, default values, etc.
http_parameters/3	Get HTTP GET or POST form-data, applying type validation, default values, etc.
http_path.pl  -- Abstract specification of HTTP server locations
location/3	Multifile hook used to specify new HTTP locations.
http_absolute_location/3	Path is the HTTP location for the abstract specification Spec.
http_absolute_uri/2	URI is the absolute (i.e., starting with http://) URI for the abstract specification Spec.
http_clean_location_cache/0	HTTP locations resolved through http_absolute_location/3 are cached.
http_proxy.pl  -- Use HTTP network proxies
http_pwp.pl  -- Serve PWP pages through the HTTP server
pwp_handler/2	Handle PWP files.
reply_pwp_page/3	Reply a PWP file.
http_redis_plugin.pl  -- Hook session management to use Redis
http_server.pl  -- HTTP server library
http_server/1	Create an HTTP server using http_dispatch/1 for handling requests.
http_server_files.pl  -- Serve files needed by modules from the server
serve_files_in_directory/2	Serve files from the directory Alias from the path-info from Request.
http_server_health.pl  -- HTTP Server health statistics
health/2	Multifile extensible.
hide/1	Multifile hook.
server_health/1	HTTP handler that replies with the overall health of the server.
http_session.pl  -- HTTP Session management
http_close_session/1	Closes an HTTP session.
http_current_session/2	Enumerate the current sessions and associated data.
http_in_session/1	True if SessionId is an identifier for the current session.
http_open_session/2	Establish a new session.
http_session_assert/1	Versions of assert/1, retract/1 and retractall/1 that associate data with the current HTTP session.
http_session_assert/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_session_asserta/1	Versions of assert/1, retract/1 and retractall/1 that associate data with the current HTTP session.
http_session_asserta/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_session_cookie/1	Generate a random cookie that can be used by a browser to identify the current session.
http_session_data/1	True if Data is associated using http_session_assert/1 to the current HTTP session.
http_session_data/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_session_id/1	True if SessionId is an identifier for the current session.
http_session_option/1	True if Option is a current option of the session system.
http_session_retract/1	Versions of assert/1, retract/1 and retractall/1 that associate data with the current HTTP session.
http_session_retract/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_session_retractall/1	Versions of assert/1, retract/1 and retractall/1 that associate data with the current HTTP session.
http_session_retractall/2	Versions of assert/1, retract/1 and retractall/1 that associate data with an explicit HTTP session.
http_set_session/1	Overrule a setting for the current or specified session.
http_set_session/2	Overrule a setting for the current or specified session.
http_set_session_options/1	Set options for the session library.
session_setting/2	Find setting for SessionID.
http_sgml_plugin.pl  -- Parse of HTML and XML documents for the HTTP client libs
http_stream.pl  -- HTTP Streams
http_unix_daemon.pl  -- Run SWI-Prolog HTTP server as a Unix system daemon
http_wrapper.pl  -- Server processing of an HTTP request
hub.pl  -- Manage a hub for websockets
current_hub/2	True when there exists a hub Hub with Name.
hub_add/3	Add a WebSocket to the hub.
hub_broadcast/2	Send Message to all websockets associated with Hub for which call(Condition, Id) succeeds.
hub_broadcast/3	Send Message to all websockets associated with Hub for which call(Condition, Id) succeeds.
hub_create/3	Create a new hub.
hub_member/2	True when Id is a member of the hub HubName.
hub_send/2	Send message to the indicated ClientId.
js_grammar.pl  -- JavaScript grammar
js_token/3	Matches and classifies the next JavaScript token.
js_write.pl  -- Utilities for including JavaScript
javascript/4	Quasi quotation parser for JavaScript that allows for embedding Prolog variables to substitude identifiers in the JavaScript snippet.
js_arg/3	Same as js_expression//1, but fails if Expression is invalid, where js_expression//1 raises an error.
js_arg_list/3	Write javascript (function) arguments.
js_call/3	Emit a call to a Javascript function.
js_expression/3	Emit a single JSON argument.
js_new/4	Emit a call to a Javascript object declaration.
js_script/3	Generate a JavaScript script element with the given content.
json.pl  -- Reading and writing JSON serialization
atom_json_dict/3	Convert between textual representation and a JSON term represented as a dict.
atom_json_term/3	Convert between textual representation and a JSON term.
is_json_term/1	True if Term is a json term.
is_json_term/2	True if Term is a json term.
json_dict_pairs/2	This hook may be used to order the keys of an object.
json_read/2	Read next JSON value from Stream into a Prolog term.
json_read/3	Read next JSON value from Stream into a Prolog term.
json_read_dict/2	Read a JSON object, returning objects as a dicts.
json_read_dict/3	Read a JSON object, returning objects as a dicts.
json_write/2	Write a JSON term to Stream.
json_write/3	Write a JSON term to Stream.
json_write_dict/2	Write a JSON term, represented using dicts.
json_write_dict/3	Write a JSON term, represented using dicts.
json_write_hook/4	Hook that can be used to emit a JSON representation for Term to Stream.
json_convert.pl  -- Convert between JSON terms and Prolog application terms
current_json_object/3	Multifile predicate computed from the json_object/1 declarations.
json_object/1	Declare a JSON object.
json_to_prolog/2	Translate a JSON term into an application term.
prolog_bool_to_json/2	JSON is the JSON boolean for Prolog.
prolog_to_json/2	Translate a Prolog application Term into a JSON object term.
mimepack.pl  -- Create a MIME message
mime_pack/3	Pack a number of inputs into a MIME package using a specified or generated boundary.
mimetype.pl  -- Determine mime-type for a file
charset/3	Hook that determines the Charset for File that has media type MediaType.
mime_extension/2	Hook that is called by file_mime_type/2 before the default table is examined.
file_content_type/2	True if File should be served using ContentType: ContentType.
file_content_type/3	True if File should be served using ContentType: ContentType.
file_mime_type/2	True when MimeType is the mime-type to be used for sending FileName.
term_html.pl  -- Represent Prolog terms as HTML
thread_httpd.pl  -- Threaded HTTP server
schedule_workers/1	Hook called if a new connection or a keep-alive connection cannot be scheduled immediately to a worker.
http_add_worker/2	Add a new worker to the HTTP server for port Port.
http_close_connection/1	Close connection associated to Request.
http_current_server/2	True if Goal is the goal of a server at Port.
http_current_worker/2	True if ThreadID is the identifier of a Prolog thread serving Port.
http_enough_workers/3	Check that we have enough workers in our queue.
http_requeue/1	Re-queue a connection to the worker pool.
http_server/2	Create a server at Port that calls Goal for each parsed request.
http_server_property/2	True if Property is a property of the HTTP server running at Port.
http_spawn/2	Continue this connection on a new thread.
http_stop_server/2	Stop the indicated HTTP server gracefully.
http_workers/2	Query or set the number of workers for the server at this port.
message_level/2	Determine the message stream used for exceptions that may occur during server_loop/5.
websocket.pl  -- WebSocket support
yadis.pl  -- Yadis discovery
ssl_verify/5	Accept all certificates.
xrds_dom/2	True when XRDS_DOM is a parsed XML document for the given resource.
xrds_location/2	Discover the location of the XRDS document from the given Id.